NWS Forecast Discussion
035
FXUS61 KCTP 010152
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
952 PM EDT Mon Jun 30 2025
.SYNOPSIS...
* Stormy pattern continues tonight and tomorrow as a warm front
(today), then cold front (tomorrow) pushes through the region,
bringing a risk of strong to severe storms and locally heavy
downpours
* Drier/less humid/more comfortable conditions are likely from
mid to late week with high confidence of nice weather on
Independence Day
* Trending warmer and more muggy again early next week.
&&
.NEAR TERM /UNTIL 8 AM TUESDAY MORNING/...
Scattered to numerous showers and thunderstorms continue to move
through Central PA tonight as very high PWAT air produces
efficient downpours and locally strong winds. Rainfall amounts
as high as 4 to 5 inches have been observed in parts of
Lancaster and Lebanon Counties where multiple rounds of storms
have produced flooding.
A slow moving warm front is draped across northeast PA and was
a focus for thunderstorm activity this afternoon and evening.
As it continues to drift northeast, broad southerly flow
underneath an amplifying mid-level trough continues to generate
locally heavy downpours and locally strong wind gusts.
With the loss of daytime heating, cold pools should begin to
takeover by 10 or 11pm and storms will wane before midnight,
thus ending the threat for severe weather and flash flooding.
Given the refuel of surface water from Monday`s rain and sultry
conditions tonight, expect fog tonight into Tuesday morning,
especially where low clouds can break. It will be quite warm
and muggy with temps slowly slipping through the 70s before
reaching a low in the mid to upper 60s across the northern and
western mtns and 70-75 in the central and southern valleys.
&&
.SHORT TERM /8 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
The aforementioned mid-level trough will shift east from the
Great Lakes to the Northeast on Tuesday. Moderate mid-level flow
will overspread much of the region, including placing central
PA in the right entrance region of an upper-level jet. At the
surface, a cool front will move east across PA and will be the
primary focus for severe thunderstorm potential Tuesday
afternoon/evening.
Stronger shear profiles will be present on Tuesday and this may
result in greater storm organization/intensity including the
potential for a few supercells capable of producing large hail
and damaging wind gusts. Storms should eventually congeal into a
more solid line as the front makes closer approach, maintaining
a damaging wind threat into the Lower Susquehanna Valley. SPC
continues a Slight Risk of severe weather, primarily southeast
of the I-81 corridor. Storm motions should be a bit quicker
tomorrow, so the risk for flooding will be comparatively
lower/more isolated compared to Monday. That being said,
isolated totals of 2-3"+ in portions of the Lower Susquehanna
Valley that got hit hard on Monday could spell trouble. A Flood
Watch will likely be needed if the potential for heavy rainfall
in those areas continues to look likely.
Drier air will begin advecting into central PA late Tuesday into
Tuesday night with dewpoints dropping well into the 60s.
Clearing skies behind the front will likely support fog
formation, with the highest risk of reduced visibility occurring
west of I-99 and in the valleys northeast of Harrisburg up into
the Wilkes-Barre/Scranton area. Lows by Wednesday morning will
range from the low 70s in southeast PA (where cloud cover will
hang on the longest) to the upper 50s in the northwest
mountains.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
In the wake of the cold front passing east of the area by
Wednesday morning, high pressure begins to build southwest of
the region, providing fair weather for the middle of the week
and into the weekend. Best chances for precipitation through
Saturday will remain due to a cold frontal passage across the
northern half of Pennsylvania. Cold front remains relatively
moisture-starved; however, generally think forcing will be
enough to cause a shower and afternoon/evening thunderstorm.
The biggest feature of the post-frontal airmass will be much
lower dewpoints and refreshing nights/mornings. There is high
confidence in lows dropping into the 50s and low 60s Thursday
and Friday nights, which will be a significant and welcome
change from the long-duration heat/humidity we have experienced
over the past few weeks. Independence Day activities should be
under fair skies, comfortable temperatures, and pleasant
northwest winds.
Low pressure approaching the Great Lakes by Sunday morning will
bring about increasing chances for precipitation for the second
half of the weekend and into the beginning of next week.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Scattered showers and thunderstorms continue late this evening
with periodic restrictions expected. The coverage and intensity
of showers should taper off by 04Z with only lingering light
showers possible overnight.
The overnight forecast is a little tricky - a mix of conditions
are expected with a potpourri of the following restrictions
possible: visibility reductions in scattered showers/storms;
visibility and perhaps ceiling restrictions in patchy dense
fog, and ceiling restrictions in low clouds.
During the day on Tuesday, more showers and storms are expected
ahead of a cold front that will traverse the region during the
afternoon and evening. Have tried to time out the best window
for thunderstorms potential at all TAF sites, with the heaviest
rain/strongest storms likely at MDT and LNS.
Outlook...
Tuesday Night...Clearing skies with patchy to widespread fog
possible.
Wed...AM fog, then VFR.
Thu...Primarily VFR; stray PM shower/t-storm possible.
Fri-Sat...AM fog possible; otherwise VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert/Banghoff
NEAR TERM...Lambert/Banghoff
SHORT TERM...Lambert/Banghoff
LONG TERM...Banghoff/NPB
AVIATION...Lambert/Martin
NWS CTP Office Area Forecast Discussion
